I threw the question out to twitter:
The results are thinner than I'd hoped for. Apparently did a survey of their customer base, which showed a huge increase in satisfaction, and a small potential increase in utilization. However, it's a self-selected group, not statistically significant, and self-reported. I was hoping for actual ridership statistics from a transit agency.
Tim Moore reported that at , they have no data on ridership impact. I'm hoping that they will start collecting it. Jay Nath asks a good question: if a transit system has good on-time performance, does real-time data matter as much as just publishing the scheduled time? (I know I'm pretty happy with the BART scheduled time I get in Google Maps; it's usually close enough.)
If anyone has more information on the following UK studies, particularly links to them, I'd appreciate it.
I got a number of suggestions for people who might know more. However, none of them have yet weighed in on the question.
And, of course, some anecdotal evidence from satisfied customers, which I include for the references to specific transit apps that people might find useful.